Winnebago River IA 02-WIN-826

Assessment Comments

Assessment is based ontwo water quality studies conducted for Lehigh Cement Co. in 1994-95.

Basis for Assessment

Continue to use the assessment of support of the Class B(WW) aquatic life uses developed for the 1996 report (=FST).   The biological information gathered for the 1994 and 1995 UHL studies, however, suggests the need to conduct follow-up monitoring in this reach of the Winnebago River.   That is, both the fish community diversity and the number of expected fish taxa from both studies were relatively low.   Upstream from the LPCC outfall, the fish community diversity (9 species from 5 families in 1994 and 9 species from 6 families in 1995) was relatively low for given the intensive sampling of a Class B(WW) stream in the Iowan Surface subecoregion (47c).   Downstream from the outfall, fish community diversity was somewhat lower, with 5 species from 3 families collected in 1994 and 8 species from 4 families collected in 1995.   Again, these numbers are relatively low for Iowan Surface streams.   The number of expected fish taxa at both sites in both years (3 of 11) was also low for Iowan Surface streams and suggests a potential water quality impact.   Follow-up monitoring is needed to better determine the status of the aquatic communities of this reach of the Winnebago River and to determine whether the Class B(WW) uses may be impaired.   Any water quality impacts identified are likely to be limited to the Mason City urban/industrial area.